The present invention relates to a water-based polymeric composition that can be used to prepare a dust-free, tack-free, solvent-resistant coating.
Coatings provide protective barriers for a variety of things including floors, automobiles, exteriors and interiors of houses, and human skin. Protective coatings for floors, for example, have been known since the mid 1950s. Many of the early coating materials were applied using petroleum- or naphthene-based solvents and as such, were undesirable due to the toxicity and flammability of these solvents.
Water-based synthetic emulsion compositions, such as styrene resin emulsions, styrene-acrylate copolymer resin emulsions, and acrylate emulsions, developed in the early 1960s, gradually replaced organic solvent-based compositions. Although these water-based compositions are less toxic and more environmentally friendly than organic solvent-based compositions, the water-based compositions tend to be slow to become tack-free and dust-free.
Removable, water-based coatings are known. For example, polymers that contain ammonium carboxylate functionality are water compatible, but become incompatible through the loss of solvent and ammonia. ##STR1##
Coatings made by the above-illustrated process can be subsequently removed by contact with an aqueous alkaline liquid, which converts the acid back into the water-compatible salt.
For example, in U.S. Pat. No. 4,622,360, Gomi et al. discloses a removable water-borne polyurethane resin containing carboxyl groups. Coating compositions can be prepared by adding a polyvalent complex-forming metal to the water-borne resin. The polyvalent metal forms a stable water-dispersible complex with the resin in the aqueous solution. When the dispersion is applied to a floor surface, volatile materials evaporate to allow the polyvalent metal ions to initiate a crosslinking of two or more carboxyl groups, thereby forming a hardened, water-incompatible coating that dries in about 30 minutes. This hardened coating can be removed with an alkaline remover solution containing, for example, potassium oleate and ammonia.
The ammonium carboxylate coating that contains the polyvalent metal is water-resistant as compared to the coating that does not contain the metal. Nevertheless, the coating takes about 30 minutes to dry. It would be an advantage to prepare a water- and solvent-resistant coating that becomes dust-free and tack-free in less than 5 minutes.